Here are two astonishing facts:
1. Our jazz bands play 43.5% of the all their tunes in just one key - Bb.
2. Our bands play over 90% of all their tunes in just three keys - Bb, F and Eb.
And yet there are twelve keys available. So why use only three?
Knowing many of my readers are not musicians, I will try to explain things as simply as possible.
When a band is going to play a tune, the musicians have to agree on which key they will use. Twelve keys are available:
G
Ab
A
Bb
B
C
Db
D
Eb
E
F
Gb.
Think of it this way: on a piano, Ab, Bb, Db, Eb, and Gb are the black notes. All the others are white notes.
The key indicates within which scale the tune is played and also which is the 'Home' note. For example, a tune in F will usually end on the note F.
The 'top five' keys are:
The 'top five' keys are:
43.5% of all tunes: Bb : (made up of 42% in Bb and 1.5% in the related minor key - G minor)
29.5% of all tunes: F : (made up of 26.5% in F and 3.5% in the related key of D minor)
18.5% of all tunes : Eb
4.5% of all tunes : C
3.5% of all tunes : Ab : (made up of 2% in Ab and 1.5% in the related key of F minor)
Of course, any tune could be played in any key. To change a tune from one key to another, all you have to do is raise or lower all the notes by the same amount in order to reach the key you want. But most tunes are traditionally played in one agreed key.
Bearing in mind that there are twelve keys available, why on earth do we find that almost half of our tunes are played in Bb? And why are most of the others played in either F or Eb?
Put simply, it is because those are the keys in which the various musicians of the band are most likely to stay well in tune with each other. For example, when a trumpet plays in these keys (especially Bb), the notes require minimal use of the valves and all notes are reasonably well in tune. Other keys require far greater uses of the valves. Each of the three valves on a trumpet adds an extra bit of tubing through which the column of air has to pass. Notes at six different pitches can easily be achieved by any combination of valves; but the physics of sound would require the length of tubing to be slightly different for each of these six notes to be perfectly in tune. So the manufacturers compromise by making tubes of the 'least worst' lengths.
On most instruments, the lower notes played with the use of valves are a tiny bit sharp. Some manufacturers provide expensive instruments with levers to extend the tubing just a little on these particular notes. You can see such levers in the centre of this picture:
The keys of Bb, F and Eb are used so much that musicians become increasingly comfortable with them and the fingering they require. So there is not much incentive to use other keys - even just for fun or for practice.
This is why traditional jazz musicians sometimes find it tricky when suddenly asked to play a tune in an unfamiliar key. This happens mostly when they accompany singers. You play a tune for years in F and then come across a singer who wants it in D because that is the key that best suits her voice.
Despite all I have said, the young band Tuba Skinny - in this as in so many respects - has made us re-think our attitudes. They are unafraid of 'tricky' keys and may be heard in a few of their recordings and YouTube videos playing in such keys as G.
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How 'scientific' is the survey above?
Sufficiently, I think, to justify my findings.
I chose two hundred different tunes from the standard traditional jazz repertoire and noted the keys in which they were played in YouTube videos and in performances I have attended. I omitted tunes such as early rags which usually comprise two or three sections and use different keys for different parts. I also omitted a very small number of tunes (such as 'Willie the Weeper' and 'At The Jazz Band Ball') which have two parts - one in a minor key and the other in the related major.
In the case of tunes in minor keys, as shown above I counted them within the total for the related major key: for example, G minor uses the same notes as Bb, so I classified it within 'Bb'.
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